In a principal aspect, the present invention relates to a liquid reduction and treatment apparatus and method for processing an influent liquid including at least a solvent and non-volatile impurities by combining the liquid with a gas or vapor to form a precipitated sludge. Typically, such a liquid is an aqueous solution formed as a by-product of landfill operations and a gas or vapor is air. The liquid may also contain volatile impurities.
A particular problem associated with solid waste facilities such as landfills is the disposal of liquid wastes resultant from waste contact with infiltrating surface and/or ground waters and the biodegradation of the solid wastes. These liquid wastes are known as leachates, and are typically of high organic strength. Often, they contain a potpourri of dissolved metals and salts. Various volatile organic compounds at various concentrations may also be present in these leachates.
These leachates most often comprise a solvent, such as water, and non-volatile impurities in solution, such as salts. Volatile impurities, either in solution or mixed in the solvent, such as organic liquids, may also be present. In particular, landfill leachates have been said to include water, suspended solids, salts such as ammonium salts, potassium salts, chloride salts, sulfates, and volatile organics, such as alcohols, acids, ketones and aromatics. Landfill leachates often contain microbiological constituents such as bacteria, viruses, fungi and parasites. However, the character of a specific leachate will be dependent upon the character of the wastes in the landfill which generate it. An excellent source of background information regarding landfill leachates is J. Lei, B. Eichenberger, and R. Stearns, Leachate From Municipal Landfills: Production and Management, Noyes Publications (1985).
Due to the difficulty and expense to treat leachates, traditionally leachates have been allowed to accumulate within the landfills, thus relying on the dilution and natural attenuative characteristics of the landfill's clay soil liners for treatment as these liquids slowly seep through them.
Because clay liners are relatively impermeable, the leachate levels within landfills can get quite high, which results in increased hydraulic heads and/or exfiltration rates and potentially leachate seeps on exterior sideslopes. In order to reduce the potential for ground and surface water contamination resultant from migration of landfill leachates, there has been ever increasing emphasis placed upon leachate collection and treatment. In fact, the USEPA has proposed and the Illinois EPA has recently adopted rules requiring leachate collection and treatment.
To date, leachate treatment has been very limited and the units used traditionally have been for sewage and other weaker wastewater treatment. Leachate treatment using these traditional processes and treatment techniques is expensive and the resultant treated effluent may still contain excessive total dissolved solids concentrations due to the waste's initial high strength.
In a typical liquid treating apparatus, such as an apparatus for the treatment of polluted liquids or sewage, a multiplicity of vessels are typically employed to separate solids from the liquid to be treated and/or encourage aerobic or anaerobic degradation of the pollutants contained in the liquid to be treated. Complex washing and settling apparatus have been devised, as well. Devices of this type are typically complex and expensive both to build and to operate. Examples of this type of device are disclosed in U.S. Pat. No. 3,811,572, issued to Tatterson on May 21, 1974; U.S. Pat. No. 3,723,309, issued to Garcia on Mar. 27, 1973; U.S. Pat. No. 3,567,629, issued to Ayers et al. on Mar. 2, 1971; and U.S. Pat. No. 3,010,581, issued to Knapp et al. on Nov. 28, 1961.
A problem associated with many of these devices is that filtration processes are slow and exacting. Filtration equipment is expensive and cumbersome because it often must be designed to accommodate a specific precipitate. Filtration also requires continual upkeep of the equipment, such as changing filters, removing filtrate, etc.
Yet another problem associated with liquid treatment devices of this type is that they require a relatively sophisticated design effort specific to the liquid to be treated. Often employing many different stages, these devices are limited in their ability to accommodate different liquids or function under different operating conditions. Moreover, these devices require strict operator control of flowrates, retention times, etc. in order for effective treatment of the liquid to be processed.
Yet another problem associated with liquid treatment devices of this type, particularly sewage or landfill treatment apparatus, is the disposal of leachate and/or landfill gases. These gases, by-products of the decomposition of the sewage or solid wastes, contain methane. Although there is considerable value in the gases due to their potential energy content, the gases are utilized on a very limited basis due to the high costs associated with upgrading their quality and/or transmitting them to a user or a natural gas pipeline.
The present invention constitutes a liquid reduction and treatment apparatus and method for processing an influent liquid that seeks to overcome these problems while at the same time providing a simple, easily constructed design and method that is readily adaptable to a variety of liquids to be processed.